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- 저자 : 윤영준(Yung Joon Yoon) (검색결과 3 건)
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관상동맥 CT조영 검사시 선량감소 프로토콜에 관한 연구
윤영준(Yung Joon Yoon),김문찬(Moon Chan Kim),남윤철(Yoon Chul Nam) 대한CT영상기술학회 2009 대한CT영상기술학회지 Vol.11 No.1
Purpose To evaluate the feasibility of using relative low tube voltage scan protocols for low-dose about prospective and retrospective ECG gating scan on coronary image quality evaluation with 64-row MDCT. Materials and methods A female ART 300 phantom was used to simulate coronary artery of size(5mm in diameter) with four stenosis degrees(0%, 25%, 50% and 75%) at 55bpm heart rate. Cardiac scans were performed on a 64-row MDCT scanner(GE LightSpeed VCT) with rotation time of 350msec, 350mm scan length with proximal-middle coronary artery and two scan methods of prospective scan(axial) and retrospective scan(helical) of 0.2 pitch under each tens different scan protocols. Tube voltage and current were 100kVp/300~600mA, 120kVp/300~600mA, 140kVp/300~400mA. The simulative coronary arteries were filled with contrast media to reach an approximate value 400HU in the lumen. Background noise was measured to describe the basic image quality accordingly. CNR, SNR and contour sharpness represented in slope of CT density curve was calculated as well. Measured stenosis area and rates, described by the percentage area of stenosis on the cross-section images were also calculated. Comparative analysis standard stenosis rate with measured stenosis rate and the error are measured. Results Dose(CTDIvol) were 7.4~22.3mGy of prospective scan and 24.3~73.1mGy of retrospective scan by the protocols. Prospective scan method was measured less 30.5% radiation dose than retrospective scan. The corresponding image noise levels described in standard deviation of background signals varied with radiation dose, CNR and SNR mainly varied with tube current. The contour sharpness, which can reflect actual spatial resolution, is affected mainly by tube voltage. When comparing the groups with similar radiation dose of prospective(protocol 10) and retrospective(protocol 1) scans, prospective scan was measured obviously steeper mean slope value than retrospective scan. Significant difference stenosis rate error presented between two groups, which is low dose and high dose. Low dose group was overestimated on stenosis rate. When comparing the groups with similar radiation dose in same scan method protocol, protocols with lower tube voltage gained more accuracy in representing stenosis area and rate. Conclusion Prospective scan was estimated similar or higher results than retrospective scan in image quality evaluation as well as lower dose. Dose level and corresponding image quality is relevant to the accuracy of stenosis evaluation on simulated coronary arteries with 64-row MDCT. In this study, we find relative low-dose protocols with acceptable image quality showed a tendency of overestimating stenosis. Furthermore, prospective scan method take an effect reduced dose in condition keep stabile heart rate and using a lower tube voltage and higher tube current to gain accurate imaging result is more applicable than other protocols with the same radiation dose level.
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윤영준(Yung Joon Yoon),김민찬(Min Chan Kim),김문찬(Moon chan Kim) 대한CT영상기술학회 2007 대한CT영상기술학회지 Vol.9 No.1
Purpose The study aimed to conduct a comparative analysis of patients with contrast media side reaction before and after computed information processing in order to investigate the current situation, to introduce side reaction management program(SRMP), to understand the necessity of computed infonnation processing and to evaluate the usability. Materials and Methods The study was conducted on patients of one year prior to and d one year post 2004 when SRMP started to be widely used : 196 patients with side reaction among 40,368 patients who used contrast media for CT exams during the year of 2002 and 667 of 75,711 during 2006. The development d the incidence of side reaction for each year from 2000 to 2006 were investigated. Retrospective study and technical statistical analysis were used for the prevalence rate in terms of body part and type as well as the rate in terms of severity for each year of 2002 and 2006. Also the relation between the rate of patients with contrast media side reaction and the injection rate for the year of 2006 was statistically analyzed. Results The incidence of patients v.iith contrast media side reaction among total patients who experienced CT scan increased to average 0.69% after computer information processing was employed from average 0.40%. The prevalence rates in major body parts in 2002 and 2006 were 0% and 2.16% in the heart, 1.17% and 1.56% in the CT angiography, 0.57% and 0.87% in the abdomen, and 0.16% and 0.13% in the brain, respectively. The prevalence rates in terms of major type in 2002 and 2006 were 14.4% and 26.8% in the digestive system, 66.1% and 51.6% in the dermatic system, 5.7% and 9.9% in the respiratory system, 4.0% and 3.7% in the circulatory system, and 10.1%, 8.0% in the nervous system, respectively. The rates of patients with side reaction in terms of intensity in 2002 and 2006 were 87.8% and 91.8% in mild cases and 12.2% and 8.2% in severe cases, respectively. The relations between prevalence rates and the injection rate (ml/s) in major parts in 2006 were 2.16% and 3.80 in the heart, 1.56% and 3.26 in the CT angiography, 0.87% and 2.73 in the abdomen, and 0.13% and 1.46 in the brain, respectively. Conclusion The rapid increase of the frequency to side reaction after computed information processing was employed is speculated to be the result of the fact that handwriting management system before computed information processing caused much of missing data whereas computed information processing enabled the input and management of mild cases and accurate information regarding prior and post treatments. On the other hand, the finding that the patients with severe side effects decreased by 4.0% (in 2006) after computed information processing was used compared to the rate before computed information processing, despite of the increase in the rate of patients with side reaction, seem to be the results of the fact that the patients who had high risk of side reaction were taken care of in advance using computed information processing. As CT scan advances, the use of contrast media increases. Based on the results of the study, it is suggested that the risk of contrast media side reaction will decrease if the management of patients with side reaction is systematically controlled with computed information processing.
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